Twin wire paper making machine wherein the wires travel in an arc

ABSTRACT

A paper making machine has a forming section provided with two endless wires forming a narrowing zone for the formation of paper web from pulp slurry fed into the zone. Parts of wires facing each other are urged against the paper web located between them by the sue of table rolls. The invention is particularly characterized by the arrangement of the table rolls within one of the endless wire loops such that a line connecting their axes forms an imaginary arc of a cylindrical surface. Other table rolls which are located within the second closed wire loop and between the first mentioned table rolls in such manner that their periphery penetrates by a given distance into the space beyond the outer tangential plane of the first- mentioned table rolls to produce a serpinten-like path of travel for the paper web in addition to moving in an arc.

July 17, 1973' VAUHKONEN 3,746,613

' TWIN WIRE, PAPER MAKING MACHINL wmmhm Tm;

, WIRES TRAVEL. 'IN AN Am; Filed Feb. 11', 1971 2 Shouts-Sheet 1 FIG]INVENTOR: E. Vauhmonen July 17, 1973 E. VAUH NEN 3,746,613

I TWIN WIRE PAPER MAKING CHI WHERBIN THE WIRES TRAVEL IN AN C Filed Feb.11, 1971 v 2 Sheets-Sheet 2 was INVENTOR: E- VQU/7KOI7QD ATTOR-NEJSUnited States Patent 3,746,613 TWIN WIRE PAPER MAKING MACHINE WHEREINTHE WIRES TRAVEL IN AN ARC Esko Vauhkonen, Syrjalankatu 9 A 195,Jyvaskyla, Finland Filed Feb. 11, 1971, Ser. No. 114,639 Int. Cl. D21f1/00 U.S. Cl. 162--301 6 Claims ABSTRACT OF THE DISCLOSURE A papermaking machine has a forming section provided with two endless wiresforming a narrowing zone for the formation of paper web from pulp slurryfed into the zone. Parts of wires facing each other are urged againstthe paper Web located between them by the use of table rolls. Theinvention is particularly characterized by the arrangement of the tablerolls within one of the endless wire loops such that a line connectingtheir axes forms an imaginary arc of a cylindrical surface. Other tablerolls which are located within the second closed wire loop and betweenthe first mentioned table rolls in such manner that their peripherypenetrates by a given distance into the space beyond the outertangential plane of the first-mentioned table rolls to produce aserpentinelike path of travel for the paper web in addition to moving inan arc.

This invention relates to a wire section of a paper making machine. Thewire section is of the type provided with two endless wires which form anarrowing webforming zone into which the pulp slurry is conducted. Afterthis zone parts of wires pointing toward each other are pressed againstthe paper web located between them.

In prior art, paper webs were usually formed on socalled Fourdriniermachines. In these machines, the slurry flows through the slice of theheadbox onto a moving, endless wire. Thus water escapes only in onedirection through the wire. This has the drawback that the completedpaper will be asymmetric in its structure. When the machine operates athigh speed, the adjacent air interferes harmfully with the free surfaceof the pulp web which is being formed. As a result, the so-called paperformation of the product is impaired, and this is an obstacle toattempts to increase the speeds of machines. In attempts to eliminatethese drawbacks, machines have been provided in which the paper web isformed between two forming surfaces. These types of equipment are of twoprincipal kinds. According to one type the paper web is formed betweentwo wires or between a wire and a felt. The other principal typecomprises a wire and a cylinder. All the wire sections with two wiresknown in prior art have many drawbacks. It has been difficult in them tomake long enough that distance over which the wires are pressed againsteach other. In addition, dewatering of the paper web has taken placeonly by pressure exerted by the wires. It has not been possible toadjust the tension of the wires to cause sufiicient pressure of thewires against each other.

An object of the present invention is to provide a wire section of thedescribed type which does not have the drawbacks of prior artconstructions.

Other objects of the present invention will become apparent in thecourse of the following specification.

In the accomplishment of the objectives of the present invention it wasfound desirable to arrange the table rolls inside one closed wire loopwhich guide the wires and the paper Web between them to form an arc andplace the table rolls outside the wire loop and inside a second closedwire loop between each of the abovementioned table rolls so that theirperiphery projects a given distance inside the common external tangentplane of the two table rolls. The surface on which the axes of the tablerolls inside the one closed wire loop is located is at leastapproximately a part of an imaginary cylindrical surface. Thecylindrical surface may be located at least substantially in itsentirety on one side of the vertical plane which extends through theslurry feeding point, but it may also be at least substantially locatedabove or below the horizontal plane passing through the pulp feedaperture. Furthermore, requisite save-alls and water deflector platesare located inside both closed wire loops. Since in a wire section inaccordance with the present invention the table rolls within one wireloop have been placed so as to form an arc, the wire runs can be madeshorter than those in prior machines and the wires can be made to urgeagainst each other over the entire stretch along which dewatering takesplace. The pressure between the wires can be substantially altered byincreasing the tension of the wires, because each table roll locatedinside one of the two wire loops protrudes into the space beyond theexternal tangential plane upon two table rolls enclosed within the otherloop. As a result of the curved path which the wires follow, there isalso created in this region a centrifugal force effect, which adds tothe dewatering capacity. Since two adjacent table rolls on differentsides of the wire path always rotate in the same direction, dewateringthrough the wire run will alternate all the time, whereby a paper web ofuniform quality is produced.

The invention will appear more clearly from the following detaileddescription when taken in connection with the accompanying drawingsshowng by way of example only, preferred embodiments of the inventiveidea.

In the drawings:

FIG. 1 is a diagrammatic elevational view of a wire section of thepresent invention.

FIG. 2 is similar to FIG. 1 but illustrates a different embodiment.

FIG. 3 is similar to FIGS. 1 and 2 but illustrates yet anotherembodiment.

Similar parts are indicated by the same numerals throughout thedrawings.

The drawings show wire sections provided with two wires 1 and 2 whichform endless loops and which over a part of their path have beenarranged to be urged against each other. One of the wires, 1, forms theinner loop 3 and the other wire, 2 forms the outer loop 4. The course ofthe wires is guided by guiding rolls within the loops, which have beenindicated by numerals 5a in the inner loop 3 and by numerals 5b in theouter loop. The Wires are further guided by breast rolls 6a and 6b, byforward rolls 7a and 7b, by tension rolls 8a and 8b, and in the part ofthe loops where the wires 1 and 2 are urged against each other, by tablerolls 9a and 9b. The breast rolls 6a and 6b are separated by a certaindistance so that between the wires 1 and 2 which these rolls guide ontothe table rolls 9a and 9b there is formed a narrowing paper Webformingzone 10, into which pulp slurry is fed from the headbox H in thedirection of the arrow A. In the forming zone 10 there are formingtables 11a and 11b, which support the wires and through which part ofthe water in the pulp slurry is already drained.

From the paper web-forming zone 10, the wires 1 and 2 are delivered forguidance by the table rolls 9a and 9b. In all the embodiments, everysecond table roll 9b is located within the outer loop 4 and every secondtable roll 9a is located within the inner loop 3. The axes of the tablerolls 9a within the inner loop 3 have been placed so as to form an arcindicated by broken line X.

In accordance with the embodiment shown in FIG. 1 the table rolls 9awithin the inner loop have been placed to form an arc in such mannerthat the part of an imaginary cylindrical surface which they constitutelies in its entirety on the left side of the vertical plane passingthrough the slurry feeding point.

In the embodiment shown in FIG. 2, the table rolls 9a constitute a partof a cylindrical surface lying below the horizontal plane passingthrough the slurry feeding aperture.

On the other hand, according to the embodiment of FIG. 3, the tablerolls 9a are located above this horizontal plane. The table rolls 9bwithin the outer loop 4 are so placed that each one of them is locatedbetween two table rolls 9a found within the inner loop 3, so that theperiphery of the table roll 9b within the outer loop penetrates a givendistance into the space beyond the common external tangential plane ofthe two table rolls 9a within the inner loop 3, most appropriately sothat this penetration increases in the direction from the end at whichslurry is introduced towards the end at which the paper web emerges. Atthe ultimate end of the wire part, there are suction boxes 12. Withinthe inner and outer wire loops there are requisite save-alls 13a and 13band water deflector plates 14a, 14b. All requisite save-alls and waterdeflectors have not been shown for the reason that the present inventiondoes not concern them.

However, small save-alls 15 under the table rolls within the wire loophave been shown in FIG. 2.

When the table rolls have been placed in the described manner, water isdrained alternately to either side of the wire section. Consequently,uniform structure of the paper web is achieved. Since the table rollshave been placed so as to form an arc, centrifugal force also assiststhe dewatering action in the wire section.

The invention is by no means limited to the described embodiments, butmodifications within the scope of the claims are possible. For example,the table roll within the outer loop need not necessarily penetrate intothe space beyond the common external tangent plane of two adjacent tablerolls in the inner loop; it may instead tangentially touch said tangentplane.

I claim:

1. In a paper making machine, a wire section comprising two closed wireloops, a paper web forming zone enclosed by said wire loops and having anarrowing section with an aperture adapted to receive pulp slurry, meanshaving an aperture supplying pulp slurry into the narrowing section ofsaid forming zone, table rolls guiding the wires and the paper web andcomprising table rolls arranged to form an arc and located within oneclosed wire loop and other table rolls arranged to form an arc andlocated outside said one closed wire loop and inside the other closedwire loop, the arcs being located close to each other with thesecond-mentioned table rolls being located be tween the first-mentionedtable rolls and so that the peripheries of the second-mentioned rollsextend through and beyond a tangential plane passing through theperipheries of two adjacent first-mentioned table rolls.

2. A wire section in accordance with claim 1, wherein the axes of thefirst-mentioned table rolls are located substantially upon a commonimaginary cylindrical surface.

3. A wire section in accordance with claim 2, wherein said imaginarycylindrical surface extends substantially in its entirety upon one sideof a vertical plane passing through said pulp slurry supplying aperture.

4. A wire section in accordance with claim 2, wherein said imaginarycylindrical surface extends substantially in its entirety below ahorizontal plane passing through said pulp slurry supplying aperture.

5. A wire section in accordance with claim 2, wherein said imaginarycylindrical surface extends substantially in its entirety above ahorizontal plane passing through said pulp slurry supplying aperture.

6. A wire section in accordance with claim 1, further having an outletfor the paper web spaced from said means, the extension of theperipheries of the second-mentioned rolls beyond said tangential planeincreasing in the direction toward said outlet.

References Cited UNITED STATES PATENTS 3,262,841 7/1966 Embry 162-203 X3,578,561 5/1971 McCarrick et al 162352 1,241,905 10/1917 Behr 1'623183,597,315 8/1971 Notbohn et a1 162-303 3,565,757 2/1971 Jordansson162-203 X S. LEON BASHORE, Primary Examiner R. H. TUSHIN, AssistantExaminer U.S. Cl. X.R. 162203, 303

